探地雷达探测地下管线的研究

在大量的城市地下施工过程中,地下管线的保护越来越受到重视,掌握施工区地下管线的敷设又是确保地下管线安全的前提。本文结合工程实例介绍了探地雷达的基本原理以及资料处理方法,并分析了探地雷达在探测管线分布中的应用效果。     

探地雷达在厦门地下管线探测中的应用

应用RAMAC系列探地雷达进行了地下管线探测的研究。基于对城市地下管线周围介质环境的分析，设计了不同的探地雷达的工作参数，对不同类型的地下管线进行了探测，并就典型的管线异常特征进行了分析。     

探地雷达探测地下管线技术与应用实例

根据探地雷达的探测原理及技术参数影响因素，提出了工作频率的选择方法。以广州和商丘两地的两个探测实例，介绍了如何根据管径、埋深确定天线频率、天线距、采样点距、时窗等探地雷达技术参数；并选择已知埋深的管线，对波速进行实地测定，以便在探地雷达剖面上对目标体的埋深作出精确解释。     

X3M探地雷达在城市地下管线探查中的应用

论文介绍了X3M探地雷达在地下管线探查的应用,对一些典型的探测图像进行了说明,并对其工作方法提出了一些建议。     

探地雷达在地下管线普查中的应用

在分析城市地下管线的工作环境的基础上，应用美国SIR-20型探地雷达，针对地下管线探测工作设定了一套完整的应用参数和参数的选择方法，简要论述了管线的反射电磁波异常特征，为探地雷达在城市地下管线普查中的应用提供借鉴。     

探地雷达探测地下管线机理研究及实例分析

探地雷达是一种适应快速、准确探测地下障碍物而迅速发展的新型电磁仪器。探讨了探地雷达探测地下管线的机理,得出了走时曲线方程,并通过对探测实例详细地分析亦探讨了复杂条件下探地雷达资料采集和图像解释的方法,介绍了一维滤波、偏移回归、时深转换等数据处理方法和经验,验证了该方法的可行性,表明该技术具有良好地应用前景。     

复杂条件下城市地下管线探测技术的应用

在城市地下管线探测中,最常用的物探方法是电磁法和电磁波法(探地雷达).通过对这两种方法的原理、管线异常特征的介绍,提出了在复杂条件下物探方法技术的应用,目的是减少干扰因素的影响、突出目标管线异常,最终对目标管线进行精确定位定深.     

探地雷达探测地下管线的能力

这是作者摘编的有关探地雷达探测管线的一些资料.通过细致的实验,从中分析管线的粗细、材质、充填物、缺损情况及天线频率、噪音等对雷达图像的影响,对今后开展城市管线探地雷达调查工作会有所帮助.     

探地雷达在探测地下采空区范围中的应用

由放心弃的地下采空区引起的地面沉陷,已成为一种典型的地质灾害,严重影响工程建设的顺利进行。为了采取相应的治理措施,查明地下采空区的埋深及分布范围显得十分重要通过实例,简述探地雷达在探测地下采空区范围中的应用,探测目的在于确定地下采空区的深度,查明地下采空区的范围,为公路建设选线提供可靠依据。     

探地雷达在黄土地区城市地质管线探测中的应用

使用探地雷达对黄土地区城市多个拟建地铁出站口区域进行地质和地下管线探测,着重研究了黄土区的土层分布情况。结合现场实际情况分析了黄土层中存在的空洞、渗水、土体塌落等情况以及PVC管线和金属管线的探地雷达图像,归纳了在黄土地区地下管线各自的探地雷达扫描图像的特点,总结出在黄土地区应用探地雷达探测城市地质分层和管线的一般性方法和规律,应用"黑—白—黑"与"白—黑—白"的图像规律进行探地雷达图像解析,很好地指导了后续的工程施工。     

地质雷达和高密度电法在废弃矿井探测中的应用

地质雷达和高密度电法在地球物理探测方面有着各自的特点,前肯可用于探测地表浅层物体,而后者则在深层探测中占有优势.将两种方法相结合,对某建筑场地内的废弃矿井进行了探测,最后探测到了竖井的平面位置和直径、巷道埋深以及采空区的基奉形状.     

探地雷达在南京某铜矿采空区探测中的应用

采空区的存在严重威胁着当地居民的农田、地面建筑物乃至生命财产的安全。介绍了探地雷达原理和技术方法,以及数据处理和资料解释方法。以南京某铜矿采空区探测为例,探讨了探地雷达在铜矿采空区探测中的应用,修正了采空区的位置,为下一步对该采空区的整治提供了依据。     

逆时偏移在探地雷达信号处理中的应用

在探地雷达的实测资料中,由于绕射波的存在导致了地下结构图象显示不清。根据电磁波与弹性波传播的相似性,本文将地震资料处理的偏移算法 (即基于标量波动方程的逆时偏移算法)运用到探地雷达的资料处理中。结果显示,绕射波得到了很好的归位,反射体的连续性得到了加强,提高了探地雷达资料解释的分辨率。     

Internal structure of mixed-sand-and-gravel beach deposits revealed using ground-penetrating radar

ABSTRACT Mixed‐sand‐and‐gravel beaches are a distinctive type of coarse‐clastic beach. Ground‐penetrating radar (GPR) and photographic records of previous excavations are used to investigate the stratigraphy and internal sedimentary structure of mixed‐beach deposits at Aldeburgh in Suffolk, south‐east England. The principles of radar stratigraphy are used to describe and interpret migrated radar reflection profiles obtained from the study site. The application of radar stratigraphy allows the delineation of both bounding surfaces (radar surfaces) and the intervening beds or bed sets (radar facies). The deposits of the main backshore berm ridge consist of seaward‐dipping bounding surfaces that are gently onlapped by seaward‐dipping bed sets. Good correspondence is observed between a sequence of beach profiles, which record development of the berm ridge on the backshore, and the berm ridge's internal structure. The beach‐profile data also indicate that backshore berm ridges at Aldeburgh owe their origin to discrete depositional episodes related to storm‐wave activity. Beach‐ridge plain deposits at the study site consist of a complex, progradational sequence of foreshore, berm‐ridge, overtop and overwash deposits. Relict berm‐ridge deposits, separated by seaward‐dipping bounding surfaces, form the main depositional element beneath the beach‐ridge plain. However, the beach ridges themselves are formed predominantly of vertically stacked overtop/overwash units, which lie above the berm‐ridge deposits. Consequently, beach‐ridge development in this progradational, mixed‐beach setting must have occurred when conditions favoured overtopping and overwashing of the upper beachface. Interannual to decadal variations in wave climate, antecedent beach morphology, shoreline progradation rate and sea level are identified as the likely controlling factors in the development of such suitable conditions.     

Estimating geometrical parameters of cylindrical targets detected by ground-penetrating radar using template matching algorithm

In the current research, the ground-penetrating radar (GPR) method has been employed to identify physical and geometrical parameters of buried cylindrical structures using the pattern recognition approach. To achieve this goal, the well-established mathematical relationships between geometrical parameters of cylindrical target (radius, burial depth, and horizontal location) and the associated GPR hyperbolic response characteristics are employed using the template matching method. In order to validate the applicability of the template matching method in providing estimates of such parameters, the method is first examined on GPR responses of synthetic models with known geometrical parameters followed by applying on real data using two different similarity criteria including 2-D spatial convolution and normalized cross correlation in the wave number domain. In the first step, the GPR responses of 71 synthetic models encompassing one, two, and three horizontal cylinders were produced using the improved 2-D finite difference in frequency domain. Then, appropriate preprocessing sequences to reduce random noise caused by forward modeling were applied on synthetic data. The proposed algorithm applied on several synthetic model responses could estimate the known geometrical parameters of the buried cylinders with acceptable accuracy (maximum error of 15%). The template matching algorithm was also used to extract geometrical parameters of water and wastewater pipes buried in Imam Hossein Square, Isfahan city, as real GPR data. Depending on environmental conditions and subsurface host formation, the real GPR data normally contain a variety of noises; therefore, a series of appropriate objective preprocessing and processing stages were designed in order to apply on real GPR images before deploying template matching algorithm. The applicability of the template matching algorithm on real data and validity of the estimated parameters were proved based on assessing the accuracy of the estimated geometrical parameters of respective pipes through GPR response versus the measured parameters. The proposed algorithm was designed in such a way that all steps of estimating geometrical parameters of buried cylindrical targets are automatically carried out.     

Internal structure of aeolian dunes in Abu Dhabi determined using ground-penetrating radar

A ground-penetrating radar survey of aeolian dunes in the Al Liwa area of Abu Dhabi reveals a variety of dipping reflectors which are interpreted as primary sedimentary structures. The interpretation of the radar profiles has been confirmed by bulldozing trenches through the study area and comparing logged sections in the trenches with the radar profiles. NNW— SSE-orientated radar profiles, approximately parallel to the prevailing wind direction, show two sets of dipping reflectors which are interpreted as sets of cross-stratification and second- and third-order bounding surfaces. Radar profiles orientated WSW—ENE across the prevailing wind direction are dominated by concave-up reflectors which are interpreted as trough-shaped scours and sets of trough cross-stratification produced by oblique progradation of barchanoid dunes. Nested troughs, with small sets of trough cross-stratification within larger troughs, may be due to reactivation following wind reversal, or the superposition of small dunes on larger dunes and the fill of large dune troughs by smaller dunes. Convex-upwards reflectors are interpreted as linear spurs on the convex portions of sinuous dunes or erosional remnants between troughs. Overall there is a tendency for the larger second-order bounding surfaces to dip downwind, which confirms Brookfield's ideas of the relative migration paths of dunes and draa.     

地质雷达检测隧道衬砌质量中的问题研究

简要地介绍了地质雷达探测原理及运用其对隧道衬砌质量进行检测时,在现场数据采集及资料处理分析不同阶段应注意的问题。     

地质雷达应用于石油类有机污染场地调查的可行性研究

石油类物质会通过渗漏方式进入土壤,改变土壤物性和结构,对土壤、地下水环境以及人类健康产生严重影响,由此造成的地下污染已成为当前普遍关注的地质环境问题。地质雷达技术在地下油类污染区的调查中,显示有原位、无损、快速、经济等显著特点。为进一步探讨地质雷达应用于石油类有机污染场地调查的可行性,本文从地质雷达的应用原理、适用条件、实用结果等方面,分析其探测石油类有机污染的能力,并对其探测的不足和局限性进行讨论。